An arrangement of the said type of an eccentric of a reciprocating piston pump is known from EP 0 539 849 B1. According to FIG. 3 of this document, this prior art eccentric arrangement comprises a drive shaft having a shaft journal on which is fixed an eccentric unit which eccentric unit is made up of a bearing bushing having two radially inwards directed rims with cage-guided needle rollers arranged between these rims. The outer raceway for the needle rollers is formed by the inner peripheral surface of the bearing bushing, and the inner raceway is formed by the outer peripheral surface of an eccentric ring.
A drawback of this prior art is that the eccentric unit is held together on the one hand by the radially inwards directed rims of the bearing bushing and on the other hand, by the radially outwards directed rims of the eccentric ring.